Figure 1

Percentage of subjects who had regimen failure with resistance to NRTIs according to Treatment Group. For subjects in groups 1 (initial therapy = didanosine/stavudine/efavirenz), 2 (initial therapy = didanosine/stavudine/nelfinavir), 3 (lamivudine/zidovudine/efavirenz), and 4 (lamivudine/zidovudine/nelfinavir), the bars show the cumulative percentage of subjects with drug resistance at the time of the first or second regimen failure; for subjects in groups 5 (initial therapy = didanosine/stavudine/efavirenz/nelfinavir ddI/d4T/EFV/NFV) and 6 lamivudine/zidovudine/efavirenz/nelfinavir), the bars show the percentage of subjects with new drug-resistance mutations after the failure of their first regimen. Drug-resistance mutations were identified through the sequencing of the HIV-1 reverse transcriptase and protease of virus isolated from subjects with virologic failure or toxicity-related failure who had plasma HIV-1 RNA levels of at least 1000 copies/mL. From Shafer RW, Smeaton LM, Robbins GK, et al. Comparison of 4-drug regimens and pairs of sequential 3-drug regimens as initial therapy for HIV-1 infection. N Engl J Med. 2003; 349: 2304-2315, with permission of the publisher, Massachusetts Medical Society.